Rate

< 40

Regularity

Regular

P waves

None

PRI

None

QRS

> 0.12; bizarre

Rate

60-100

Regularity

Regular

P waves

Upright and uniform

PRI

0.12-0.20

QRS

0.08-0.12

Rate

60-100

Regularity

Irregular

P waves

Morphology changes

PRI

Changes

QRS

0.08-0.12